Python's comparison of floating-point and integer numbers can lead to unexpected results due to the lack of implicit type promotion and the use of infinite precision integers. CPython, a reference implementation of Python, uses a complex algorithm to compare floats and ints, which involves comparing signs, magnitudes, exponents, and actual values. That's why it's recommended to use library functions for comparing floating-point values to avoid unexpected results.

Since version 4.7, the order of properties in an object in TypeScript can affect type inference. This change was introduced to address bugs related to context-sensitive functions, but it can lead to unexpected errors when properties are reordered.

Undefined behavior (UB) in C code allows compilers to optimize code based on the assumption that no UB exists, potentially removing conditions or altering program flow. However, the handling differs between compilers if the compiler statically detects UB, like division by zero: GCC tends to crash the program, while Clang may ignore the undefined code or continue compiling, potentially leading to unexpected results later. This differing behavior is due to different philosophies - LLVM aims for more lenient handling to match developer expectations, while GCC takes a more conservative approach.